1. FIELD OF THE INVENTION
The present invention relates to a photographic light-sensitive material, and more particularly, it relates to a silver halide photographic light-sensitive material in which gelatin is used as a binder.
2. DESCRIPTION OF THE PRIOR ART
Photographic light-sensitive materials are composed of a silver halide light-sensitive emulsion layer, an emulsion protective layer, a filter layer, an intermediate layer, an antihalation layer, a backing layer, a film support subbing layer, a baryta layer, a film support and the like. Usually, gelatin is used as the main constituent of these layers other than the film support.
These photographic materials containing gelatin are treated with various aqueous solutions having different pH's and temperatures. A conventional gelatin layer has poor water resistance and swells excessively in an aqueous solution, so that the mechanical strength is greatly reduced, and, in an extreme case, the gelatin layer sometimes dissolves out, particularly when the gelatin layer is in an aqueous solution having a high temperature of above 30.degree. C or a highly alkaline aqueous solution.
These properties are fatal defects as physical properties of the layers of the photographic light-sensitive material.
In order to improve these properties of gelatin, many compounds are known and can be effectively used. Many compounds are known which are used as hardeners in the production of photographic light-sensitive materials. Examples are formaldehyde, glutaraldehyde and like aldehyde type compounds; compounds having a reactive halogen as described in U.S. Pat. No. 3,288,775 and so on; compounds containing a reactive ethylenically unsaturated bond as described in U.S. Pat. No. 3,635,718 and so on; aziridine type compounds as described in U.S. Pat. No. 3,017,280; epoxy compounds as described in U.S. Pat. No. 3,091,537; and halocarboxyaldehydes such as mucochloric acid, dioxanes such as dihydroxydioxane and dichlorodioxane, or inorganic hardeners such as chromium alum and zirconium sulfate.
However, most of these known gelatin hardeners have serious defects when they are used in photographic light-sensitive materials, in that the hardening effect is insufficient, in that the gelatin hardening rate is not sufficiently fast, so that film hardening slowly proceeds with the passage of time after the production of the photographic materials (i.e., after-hardening), in that harmful effects on photographic light-sensitive materials occur (particularly, an increase of fog, a decrease of sensitivity, etc.) in that the hardening effect is destroyed by other photographic additives which are present, in that they adversely affect other photographic additives (for example, color forming couplers for color photographic light-sensitive materials), in that the preparation thereof is difficult and a large scale of production is not appropriate, in that the hardeners per se are unstble and storage thereof are difficult, and the like. Further, some of them have a quite bad odor which causes a decrease in work efficiency during production thereof or which is harmful to the human body.
It is also known that hardeners having an active vinyl group are relatively advantageous. For example, divinylsulfone, which is an example thereof, is not practically used due to its quite harmful effect on the human body. The compounds having a vinylsulfonyl group as described in German Patent Publication No. 1,100,942, U.S. Pat. No. 3,490,911, etc., are compounds in which such a defect is improved.
These vinylsulfone type hardeners have advantages as a hardener in that they have generally a high hardening rate and a small after-hardening effect which is the variation of hardening effect with the passage of time, in that they have less harmful effects on photographic properties such as fog formation, desensitization, etc., and in that they have relatively less adverse affects on color photographic emulsions such as decoloration, etc.
However, these vinylsulfone compounds are expensive or they require a special method in which a large amount of organic solvents are used in order to use these compounds. The vinylsulfonyl compounds having an acylamide bond as described in U.S. Pat. No. 3,868,257 and Japanese Patent Application (OPI) No. 24435/74 are examples.
It should be noted, however, that the hardener in question is merely one component of many kinds of additives used in a photographic light-sensitive material which is a relatively complex system. That is, finished photographic light-sensitive materials occasionally come into contact with an atmosphere of formaldehyde vapor or they are influenced by vapors of volatile aldehydes such as methyl glyoxal, acetoaldehyde, etc., which is generated from a film support or a film support subbing layer when the photographic materials are stored under a condition of a relatively high temperature and high humidity before they are used.
In such circumstances fog formation generally occurs and, in the case of color photographic light-sensitive materials, undersirable photographic effects such as inhibition of color development, discoloration, etc., due to the reaction of a color coupler and such a vapor are observed.
It is also known that a urea type compound or a compound having an active methylene group such as dimedone as described in U.S. Pat. Nos. 2,895,827; 3,652,278, etc., is effective as a technique for preventing adverse photographic effects due to aldehyde type vapors.
However, some kinds of ureas can react with a vinylsulfonyl type hardener and so either or both of the effects of a hardener or an aldehyde scavenger by the urea are lost. In order to prevent such a defect, the use of an acyclic urea and a vinylsulfonyl hardener is described in U.S. Pat. No. 3,811,891. However, a urea type compound is generally known as hydrogen bond forming agent. That is, it has the effect for destroying the setting property, i.e., the reversible property between a sol and a gel of gelatin which is one of the big advantages why gelatin is used as photographic binder and thus the use of ureas in the production of photographic ligh-sensitive material is not preferred.